The present invention relates generally to an apparatus disposed in a printer for turning over printed papers, and particularly to a paper turnover apparatus for turning printed papers to a face-up or face-down state.
Conventional printers, particularly laser printers, are provided with a paper turnover apparatus for turning over printed papers, so that printed papers can be, in sequence, piled up on a paper receiving tray with face up or face down. FIG. 1a is a simplified diagram showing that papers to be printed are being transferred through a conventional printer and being disposed in a paper receiving tray with face up. As shown in FIG. 1a, papers to be printed are transferred through a transfer guide area 1 and a fuser area 2 for heating the papers passing therethrough and fusing carbon powders on the papers. Then, papers are transferred to the paper receiving tray 4 from under the paper guide 3. FIG. 1b is a simplified diagram showing that papers to be printed are being transferred through a conventional printer and being disposed in a paper receiving tray with face down. As shown in FIG. 1b, papers to be printed are transferred through a transfer guide area 1 and a fuser area 2 for heating the papers passing therethrough and fusing carbon powders on the papers. Then, papers are transferred to the paper receiving tray 5 by sliding over the paper guide 3.
The paper turnover device of the above conventional printer comprises a rear door (or paper receiving tray 4) and a paper guide 3. The construction of the paper guide 3 is shown in FIG. 2. As shown in FIG. 2, a plurality of claws 32 are fixed, in an, equally-spaced manner, on a solid shaft 31. The claws 32 are used for guiding papers being transferred to move upward or downward. A crank 33 is fixed on the left end portion of the shaft 31, and a coil spring 34 is accommodated within the crank 33 in such a way that one leg of the spring 34 is restrained by the inner wall of the housing of printers, and the other leg of the spring 34 is engaged with the crank 33. By this arrangement, the paper receiving tray 4 is capable of driving the claws 32 to rotate about the shaft 31 for a predetermined angular displacement. In other words, as shown in FIG. 3a, when the paper receiving tray 4 is not in contact with the crank 33, papers being transferred in the direction A will slide over the upper surface 32a of the claws 32 and move upward. When the paper receiving tray 4 is turned to a horizontal attitude (see FIG. 3b), the crank 33 will be urged by the paper receiving tray 4 to rotate in the direction B, and thus the claws will be driven to rotate a predetermined angle. At this state, papers being transferred in the direction C (same as direction A) will be guided by the bottom surface 32b of the claws 32 and move in the direction D toward the paper receiving tray 4.
As described above, the paper guide 3 comprises a lot of parts such as the claws 32, the coil spring 34, etc.. However, too many parts will incur high cost. Furthermore, it is time consuming to assemble the paper guide 3.